The Pegasus was released from Orbital's "Stargazer" L-1011 carrier aircraft at noon EDT on June 13, or 4 a.m. MHT on June 14 in the drop zone. The aircraft took off one hour before launch from Kawajalein Atoll, a small chain of U-shaped islands in the Pacific Ocean.

The 772-pound NuSTAR will spend at least two years observing high-energy X-rays more closely, in higher resolution, than any space telescope before it. On the electromagnetic spectrum, high-energy X-rays are beyond the scope of visible light and are challenging to detect. NuSTAR's advanced design uses two sets of 133 thin, nested shells of mirrors to capture the X-rays as they bounce off the reflecting surfaces at glancing angles. The expected result is an orbiting observatory that enables astronomers to see the universe in an additional band of light, advancing our understanding of how galaxies form and evolve.